Today is Ember Friday in Advent. It ranks as a greater, non-privileged ferial day of simple rite.
At Mattins the invitatory Prope est jam Dominus etc is sung and the hymn is Verbum supernum prodiens. The nocturn has three lessons from a homily of St. Ambrose of Milan on St. Luke's account of the Visitation. After the third responsory the second scheme of Lauds is sung (Pss. 50, 142, 84, the Canticle of Habacuc & 147) with the set of antiphons Constantes estote etc. This set of antiphons is the first used this year of six sets for the ferial days before the Vigil of the Nativity. The hymn at Lauds is En clara vox, the antiphon on the Benedictus is Ex quo facta est etc. After the antiphon is sung in full after the canticle the choir kneels and the ferial preces are sung.
At the Hours the same antiphons, Constantes estote etc., are used in sequence. At Prime the fourth psalm is added (the one displaced by the Miserere in the schema of Lauds II, Ps. 98) and the chapter is Pacem et veritatem. The Dominical and ferial preces are sung with the choir kneeling. At the other Hours the short set of ferial preces are sung, again with the choir kneeling.
Mass is sung after None. The ministers wear folded chasubles. Four candles are on the altar. The second collect is of the BVM, Deus, qui de Beate, and the third collect for the Church, Ecclesiae, or Deus omnium. Mass then continues as usual (with of course kneeling for the orations and from the Canon through to the Fraction as usual on penitential days) with Benedicamus Domino sung as the dismissal.
Vespers are ferial. The Office hymn is Creator alme siderum and the first of the Great 'O' Antiphon's, O Sapientia, is sung. These antiphons are 'doubled', i.e. they are sung entire both before and after the Magnificat even on days of simple rank. After the antiphon has been repeated after the Magnificat the choir kneels and the ferial preces are sung. The collect is of the previous Sunday, Aurem tuam. At Compline the Dominical preces are sung, again kneeling.
Following the 'liturgical books of 1962' at Prime the fourth psalm is not added and the ferial chapter Pacem et veritatem is replaced by the festal (!) Regi saeculorum. The ferial preces are omitted at Prime and the Hours. At Mass there is no additional collect for the Blessed Virgin or for the Church. The penitential kneeling is reduced. The dismissal is Ite, missa est and the ministers wear dalmatic and tunicle. One strange feature of 1962 Ember Wednesdays and Fridays is that whilst traditionally the Ember Day liturgy ended with the Mass sung after None, in the 1962 books Vespers becomes formally part of the Ember Day. In the traditional rite if Vespers were ferial, the collect from the preceding Sunday was sung as noted above. In the 1962 rite the collect from the Ember Day is used at Vespers, so today Excita, quaesumus is sung.